This invention relates to an ion cyclotron resonance mass spectrometer and more particularly to an improved cyclotron resonance ion source.
The ion cyclotron resonance spectrometer has come into widespread use for the study of ion-molecule reactions. With that has come considerable development in apparatus and techniques for use in such a spectrometer. For a comprehensive review of developments, see J. L. Beauchamp, "Ion Cyclotron Resonance Spectroscopy" Annual Review of Physical Chemistry, Vol. 22, pp 527-561 (1971). There the general basis for ion cyclotron resonance spectrometry is succinctly stated to be motion of a free charged particle in a uniform magnetic field, H. The motion is constrained to a circular orbit of angular frequency, W.sub.c, in a plane normal to H and is unrestricted parallel to H. When an alternating field at radio frequency is applied normal to H, absorption of energy by the ions can be observed as a decrease in total ion current or as a direct power absorption when using a marginal oscillator detector.
One problem, to which the present invention is addressed is coupling the ion cyclotron resonance experiment to a non-magnetic experiment or an experiment using a different magnetic field. Prior art cyclotron resonance mass spectrometers were relatively large, heavy and expensive. Typically, the air gap in the magnet is approximately two inches, thus requiring a large electromagnet consuming a relatively large amount of electric power. The problems of such a large electromagnet are then compounded by the difficulty of coupling the ion source in such a large electromagnet to any ion optics, primarily because of the large volume magnetic field. The large volume has the disadvantage of larger residual magnetic fields at several inches distance from the cyclotron experiment.